Hermetically sealed vessel



Aug. 8, 1939. w. J. SCOTT ET AL HERIETICALLY SEALED VESSEL Filed March 22, 1939 Inventors William J. Scott,' William T. Cowhig,

bug Their Attorney.

Patented Aug. 3, 1939 I 2,169,112

UNITED STATES PATENT OFFICE 2,169,112 HERMETICALLY SEALED VESSEL William J. Scott and William T. Cowhig, Rugby, England, assignors to General Electric Company, a corporation of New York Application March 22, 1939, Serial No. 263,358 In Great Britain October 15, 1938 9 Claims. (Cl. 176 36) This invention relates to hermetically sealed sealed. A portion ll of the tube l3 extends into vessels and method of hermetically sealing such the interior of theenvelope. Leading-in wires vessels, more particularly to envelopes of elec- I5 also pass through the stem l2 and carry a trio lamps, discharge devices or the like. filament l6 at their inner ends. In addition to 5 Where such vessels are evacuated or where these leading-in wires, a third wire I! is sealed 6 the pressure within them is reduced considerably into the stem, and connected between this wire below atmospheric pressure, the hermetic sealing l1 and one of the leading-in wires I5 is a heating presents little difficulty since owing to the prescoil I 8 which surrounds the tubular extension sure within being less than that outside the deor re-entrant tube l4. After suitably adjusting 10 vice, when heat is applied to the glass tubulature the gaseous content of the vessel by the evacua- 10 through which the vessel is evacuated, the walls tion-or filling thereof, the heating coil I8 is conof the tube collapse as the glass softens. When, nected to a source of current through the leads l5 however, the pressure within the envelope or vesand I! so that the glass tube It is heated up to its sel approaches or exceeds atmospheric pressure melting point and the end closes. If desired, the

the operation of scaling is more difiicult, as the closure may be aided by mechanical pressure on walls of the tube will not collapse and may even the tube from a spring or weight. When the expand outwardly when they are softened. seal is completed, the tube l3 may be connected An object of the present invention is to proto a vacuum, pump and sealed off at a point outvide an improved method and means for sealside the envelope if desired.

ing vessels of the above type. In Fig. 2 we have shown a lamp in which a The invention utilizes a fusible part which re-entrant tube I9 is secured to the envelope extends within the interior of the vessel and I0 on the opposite side of the bulb from the which preferably, although not necessarily, constem l2. Otherwise the'arrangement is similar stitutes a continuation of the tube through which to that illustrated in Fig. 1.

the vessel is exhausted. In accordance with the In Fig. 3 we have shown a lamp stem l2 and u inven i the portion of the part which is withfilament l6 assembled for mounting in a bulb in the vessel is softened by conduction, convecin which the heating coil l8, instead of being tion, radiation or by a combination of two or provided with aseparate lead, is connected across more of these methods. As a result of the fact the leading-in wires l5 which carry the filament that both the inner and outer surfaces of the IS. The heater l8 in this case is so designedas part are subjected to substantially thesame presto dimensions and current-carrying capacity sure, it may readily collapse when fused by this that it may be made to heat the tube It to the means to form a fused closure for the exhaust desired temperature during sealing but will burn opening. If desired, mechanical pressure suitoutupon application of the voltage applied to ably applied to the fusible part may be used to the filament 5 during normal operation thereassist the collapse of the part upon fusion. of, so that it does not short circuit the filament For a more complete understanding of our inthereafter. In addition, a suitable shield 2|, vention, reference should be had to the accomu h a a sheetof mica, is provided b twe th pourin d aw in w c 1 s a sectional filament l6 and heating coil in to protect the View of an electric lamp arranged for sealing acfilament from damage during li Ordmg our invention; 2 is a side elem" In Fig. 4 we have shown a further modification tional View of an j? lamp P of our invention in which means other than a entrant sealing tube positioned at a point other heating coil is provided to fuse the glass than in the lamp stem; Fig. 3 is a sectional view of a lamp stem provided with a shield between g g zri fg g 5 :2 i g g ggfifi 5 the filament and a heater coil which is connected across the filament leads; and Fig 4 is a tiv ty to facilitate inductive heating thereof potj l View f a iamp stem provided with an sitioned in heat exchanging relation with the ductive heater illustrating a further embodiment tube- The partlcfllar element Shown comlnlses of our invention. an inverted cup-l1ke metal member 22 Whlch is w Referring now to the drawing, Fig. 1 illusarranged o enclose the ity of the tube trates a lamp having a. glass envelope in which and which is supported thereon by a suitable may be evacuated or contain a gas at any deelement 23. When the envelope has been evacsired pressure. Sealed into the base of this enuated or filled to the desired pressure, the tube velope is a stem I2 through which a tube I3 is or cap is heated inductively by a high frequency ail? electromagnetic field so as to cause softening and fusion of the tube II.

The heater coil in any of the modificationsillustrated in Figs. 1 to 3 may be conveniently made of tungsten wire or a wire which may act as a getter, or the heating coil illustrated in any of these figures may be inductively heated. In the latter case it need not be connected across the leading-in wires, but may be supported from one only or may be wound around the re-entrant tube for support.

It will also be noted that in each case we have illustrated our invention with a glass sealing tube. It should be understood, however, that this tube need not be made wholly of glass but that its inwardly protruding end may be provided with a suitable sealing composition, such as an alloy of iron and chromium having substantially the same coefficient of expansion as the glass portion of the tube H. The modifications shown in Figs. 3 and 4, of course, are intended to be used in vessels similar to the one illustrated in Fig. 1.

While we have-shown particular embodiments of our invention, it will be understood, of course, that we do not wish to be limited thereto since many modifications may be made, and we therefore contemplate by the appended claims to cover any such modifications as fall within the true spirit and scope of our invention.

What we claim as new and desire to secure by Letters Patent of the United States is:

l. The method of preparing and sealing a vessel which comprises forming within the vessel an inwardly extending member having an opening therein, utilizing said opening to adjust the gaseous content of the vessel to a desired value, and thereafter applying heat to said member sufiicient to fuse a portion of said member at a point within said vessel and thereby to seal said opening.

2. The method of preparing and sealing a vessel which comprises forming within the vessel an inwardly extending member having an opening therein, evacuating said vessel through said opening, and applying heat to said member sufficient to fuse a portion of said member at a point within said vessel and thereby to seal said opening.

3. The method of preparing and sealing a vessel which comprises forming within said vessel an inwardly extending member having an opening therein, filling said vessel with a charge of suitable gas through said opening, and applying heat to said member suflicient to fuse a portion of said member at a point within said vessel, thereby to seal said opening.

4. The combination in a gas tight vessel of means for adjusting the gaseous content of said vessel including a re-entrant member extending inwardly into the interior of said vessel, said member having an opening communicating therethrough with the exterior of said vessel, means for heating said re-entrant member at a point within said vessel to cause a portion of said member to collapse under the pressure of the gas surrounding it and fuse together thereby sealing said opening.

5. The combination in a gas tight vessel of means for adjusting the gaseous content of said vessel to a desired value comprising a re-entrant member extending inwardly into the interior of said vessel, said member having an opening communicating therethrough with the exterior of said vessel, fusible means for sealing said opening in said re-entrant member at a point within the interior of said vessel, and means for applying heat to said fusible means in said vessel thereby to seal said opening.

6. In a gas tight vessel having an electrical filament therein and a pair of leading-in conductors connected to said filament and extending through a wall of said vessel, the combination which includes means for adjusting the gaseous content of said vessel comprising a reentrant member projecting into said vessel and having an opening therein, and means including a heater coil for applying heat to a portion of said re-entrant member sufficient to fuse it at a point within the interior of said vessel and thereby to seal said opening, said heater coil being connected to said leading-in wires and adapted to burn out upon application of the voltage to be applied to the filament during normal operation thereof.

'7. In a gas tight vessel having an electrical filament therein and a pair of leading-in conductors connected to said filament and extending through a wall of said vessel, the combination which includes means for adjusting the gaseous content of said vessel comprising a reentrant member projecting into said vessel and having an opening therein, heater coil for applying heat to a portion of said re-entrant member sufficient to fuse it at a point within the interior of said vessel and thereby to seal said opening, said heater coil being connected to said leading-in wires and adapted to burn out upon application of the voltage to be applied to the filament during normal operation thereof, and protective means including a shield interposed between said heater coil and said filament.

8- In a gas tight vessel having an electrical filament therein and a pair of leading-in conductors connected to said filament and extending through a wall of said vessel, the combination which includes means for adjusting the gaseous content of said vessel comprising a reentrant member projecting into said vessel and having an opening therein, and means for ap-- plying heat to a portion of said re-entrant member suflicient to fuse it at a point within the interior of said vessel, said last-named means including an element of sufiicient conductivity to facilitate inductive heating thereof positioned in heat-exchanging relationship with said portion of said re-entrant member.

9. In a gas tight vessel having an electrical filament therein and a pair of leading-in conductors connected to said filament and extend ing through a wall of said vessel, the combination which includes means for adjusting the gaseous content of said vessel comprising a reentr-ant member projecting into said vessel and having an opening therein, a heater coil for applying heat to a portion of said re-entrant member sufiicient to fuse it at a point within the interior of said vessel and thereby sealing said opening, a third leading-in wire, said heater coil being connected to one of said pair of leading-in wires and to said third leading-in wire.

WILLIAM J. SCO'I'IT. WILLIAM T. COWHIG.

means including a U 

